Chlorophyll fluorescence in the evaluation of photosynthetic electron transport chain inhibitors in the pea

Abstract

-The study aimed to evaluate the behavior of the chair of photosynthetic electron transport in the presence of DCMU and atrazine in detached leaves of pea through simultaneous measurements of the kinetics of fluorescence transient, fluorescence delayed and modulated reflection at 820 nm. The petioles of the leaves were immersed for two hours in solution of inhibitors at concentrations of 0 (control), 25, 50, 100, 250 and 500 M. Measurements of the kinetics of fluorescence transient and fluorescence delayed and modulated reflection at 820 nm were recorded simultaneously by the M-PEA fluorometer. Simultaneous measurement of fluorescence transient, fluorescence delayed and modulated 820 nm reflection is important for assessments of the photosynthetic electron transport chain activity tool. The use of specific inhibitors of the electron transport chain allows you to collect and correlate a lot of information about the effect of different inhibitors at specific points in the photosynthetic electron transport chain. DCMU and atrazine are inhibitors of photosystem II and the concentration of 500 mM affects more strongly the flow of photosynthetic electrons. RESUMO -O trabalho teve como objetivo avaliar o comportamento da cadeia de transporte de elétrons fotossintética na presença de DCMU e atrazina, em folhas destacadas de ervilha, através de medidas simultâneas das cinéticas da fluorescência transiente, decaída da fluorescência da clorofila a e reflexão modulada a 820 nm. O pecíolo das folhas foi imerso por duas horas em solução de inibidores nas concentrações de 0 (controle), 25, 50, 100, 250 e 500 µM. Medidas da cinética da fluorescência transiente, da decaída da fluorescência e reflexão modulada a 820 nm foram gravadas, simultaneamente, pelo fluorômetro M-PEA. A medida simultânea da fluorescência transiente, decaída da fluorescência e reflexão modulada a 820 nm é ferramenta importante para avaliações da atividade da cadeia de transporte de elétrons fotossintética. O uso de inibidores específicos da cadeia de transporte de elétrons permite coletar e correlacionar uma série de informações sobre o efeito de diferentes inibidores em pontos específicos na cadeia de transporte de elétrons fotossintético. DCMU e atrazina são inibidores do fotossistema II e a concentração de 500 µM afeta de maneira mais acentuada o fluxo de elétrons fotossintético. Palavras-chave:Pisum sativum L.. Fluorescência transiente. Decaída da fluorescência. DCMU. Atrazina.

Evaluation of Chalcone Derivatives as Photosynthesis and Plant Growth Inhibitors

“…The absorbed energy was expected to be released by the chlorophylls of antenna complex. Additionally, compounds 6a and 6k decreased the quantum yield parameters ΦE 0 (50 % and 22 %), ΦR 0 (56 % and 30 %) and ψE 0 (42 % and 20 %) which demonstrates an efficient mechanism for inhibiting electron transport between Q A and Q B [42] …”

“…Additionally, compounds 6a and 6k decreased the quantum yield parameters ΦE 0 (50 % and 22 %), ΦR 0 (56 % and 30 %) and ψE 0 (42 % and 20 %) which demonstrates an efficient mechanism for inhibiting electron transport between Q A and Q B . [42] Among the heteroaromatic chalcones, compounds 7b, 7e and 8b showed similar behavior to 6a as PSII inhibitors (Figure 4-Chart B). The electron transport inhibition affects PSII by reducing the parameters associated with RC and blocking the electron flow to PSI acceptors.…”

“…Additionally, the decrease of electron transport parameters ET 0 /RC and RE 0 /RC and the quantum yield parameter ΦE 0 suggest an interruption of the photosynthesis process, showing similar effects to the commercial PSII inhibitor herbicide DCMU, which blockages the electron transfer from Q A to Q B at protein D1 of PSII. [42] Furthermore, the correlation between chalcone derivatives and DCMU on PSII activity is demonstrated by the increase of V J parameter, indicating that the Q A -Q B redox process was inhibited, leading to accumulation of reduced Q A . The quantum yield of reduction of end electron acceptors at the PSI acceptor side (ΦE 0 , ΦR 0 and ψE 0 ) were also reduced by an average of 15 % to 25 %, indicating the electron chain interruption of PSII is extended to PSI.…”

Understanding the photophysics and structural organization of photosynthetic proteins using model lipid membranes assembled from natural plant thylakoids

“…66,67 Multiple studies have proposed that, by selectively switching on or off portions of the electron transfer energy process, various photochemical inhibitors can give an indirect measure of the activity of PSII. 68 Therefore, we performed a "photochemical assay" on hybrid membranes by monitoring changes to the chlorophyll fluorescence intensity (or lifetime), in response to these stimuli. In hybrid membranes as prepared, the water-soluble proteins responsible for electron transport from PSII to other proteins are likely to be missing (see Figure 6A).…”

Impact of phosphorus and luminosity on the propagation, photochemical reactions and quality of Lippia alba (Mill.) N.E.Br. seedlings

“…The results for F m and ETR is important in the photochemical process since larger values favor the flow of chlorophyll molecules between acceptors in photosystems (Farias et al, 2016). The higher photochemical efficiency in PS II effectively contributes to maintaining the integrity of the photosynthetic apparatus and increasing vegetative characteristics.…”